Hello! Welcome, I'm not sure how long you have been on the site but welcome. I wanted to start off with saying that I don't know your whole situation but I can sympathize with a lot of these feelings and have gone through similar thoughts paths and experiences with these feelings. That being said, I will do my best to adequately address your concerns from my own personal experience and from others I have talked to.
Your first sentence "What to do when you are feeling empty"
Turn to Christ to fill you up. Ask Him to fill that emptiness, ask Him why you feel empty and ask yourself what feeling full looks like to you.
When you are hurting, discouraged and not motivated anymore because of the husband's attitude.
Work hard on not letting your circumstances change your duties and reactions. This is something I have worked years on and am still working on it's a mind shift but once you get there it won't matter what you feel because your job still needs to be done. I repeat I am still working on this but it was helpful to learn a long the way. Just because your husband has a bad attitude does not mean or allow for you to have a bad attitude too. Doesn't mean it's easy but I'd encourage you to focus on that.
What if your husband is very selfish and only thinks about what he needs and want.
Are you thinking about his needs? One thing I noticed is when I am feeling selfish it's because I am self protecting for whatever reason and vice versa for my husband, if we don't think about each other's needs above our own (because ideally the other person is looking out for our needs so we don't have too) we are less likely to be out of sync.
If you are feeling like he is feeling selfish there is a chance he is feeling like you are being selfish. If that is the case I encourage you two to reconnect, talk and figure out how to meet the needs of the other person so neither of you have to look at and seek for your own needs being fulfilled if that makes sense. Also prayer works better than nagging (not saying that you are but still want to address it). Even if you are looking at his needs and are feeling like yours aren't being met after talking, then continue praying and be patient you both are in the middle of a storm for the sounds of it.
I have learned and noticed that being patient (after talking things through) and praying and letting God put your needs on your husband's heart will yield better results than nagging or begging or continuously bringing up how unsatisfied/discouraged/insert emotion here that you are feeling. This prayer should come before the conversation, during, and after.
Having the feeling of always be at the second level, his friends, siblings ans family, kids from previous marriage always come 1st?
Is that truth? Or is this just how you feel? Because there is a difference, I ask that because I noticed many times in my own relationship I would say and get upset about things that my husband has never actually said, it was my own doing for getting worked up. Not saying that is the case here but it's more a challenge for you, to actually look at what is going on. Is this truth? Is he actually putting you second? How can you tell? What would it look like for you to be #1 in your mind? What would that change? Is this actually the problem or is there something deeper there here too? Past events with previous relationships even things our close family members have gone through that you have seen can cause people to feel they are second before they actually are. I would encourage you to pray and write it out hopefully diving deeper will yield answers and peace.
The ex wife is the one dictating. When do the kids visit. According to her mood, plans and wants.
Having ex's with custody agreements is never an easy thing. I am sorry this is just adding more to the pile. I will be praying for you and your family. You have the ability to show love and be flexible and patient, extending grace, to her and as previously stated tap into the Lord's strength and let Him deal with the rest.
Being heavily pregnant, almost at terms with a baby of 1Y, having to go to work everyday, no car to use, nany and maids every weeks have e problems.
Congratulations on the pregnancy, a lot of what you are feeling is honestly probably amplified by the hormones which is totally a natural and normal thing to experience. I remember when I was pregnant the ant hills became mountains and I would often sob because it didn't make sense why these normally smaller things that I could handle felt like I couldn't handle them. That doesn't mean what you are feeling is invalid, it just means be mindful that you are sitting in a hormonal cocktail, and the sleep deprivation, young children, work and vehicle stress, family stress etc, is going to feel much heavier compared to them happening one at a time. So hopefully that's just a mental note to reassure you that you are normal for them to feel harder and bigger than if you weren't at the end of pregnancy.
As the other ladies mentioned talking to your husband is key, prayer is key, perseverance is key, clinging to Christ and your husband is a must. Especially if your husband is appearing selfish, he might just need more reassurance, love, care, and more. Especially if there is financial and vehicle problems. He is probably overly concerned with how can he provide and protect everyone and everything. I of course don't know the whole situation but again something to think about.
Hopefully this is helpful I will be praying for you and thank you for sharing.